Metal Plug Via Cavity Conformal Contact IC Fabrication
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Solution Overview
Problem
The fabrication of integrated circuits (ICs) faces challenges in reducing defects and electrical resistance in local interconnect layers due to the presence of cavities within vias, which can impede current flow and cause material migration, affecting the overall operation of the IC.
Innovation Solution
The formation of a metal plug within the cavity of a via, which conformally contacts the sidewalls and interior surface of the via, laterally distal to the exterior sidewall, and is made of a different material composition than the via, with a refractory metal liner to separate it from the contact, thereby reducing defects and improving electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a via is formed in the local interconnect layer to connect FEOL and BEOL components, then electrical connectivity is achieved, but cavities within the via cause increased electrical resistance and potential material migration
Solution Approach 1:
A refractory metal liner is deposited on the interior surface of the via to act as an intermediary barrier layer between the via wall and the conductive material. This liner prevents material migration from the via into the conductive material filling the via, thereby eliminating cavities and reducing electrical resistance while maintaining reliable electrical connectivity.
2Object-affected harmful factors
If the via is filled with conductive material to eliminate cavities, then electrical resistance is reduced, but the process complexity increases due to additional fabrication steps
Solution Approach 1:
The refractory metal liner is deposited on the via interior surface before the conductive material is introduced. This preliminary action prepares the via by creating a protective barrier layer that prevents subsequent material migration, thereby eliminating cavities and reducing electrical resistance through a systematic multi-step process.
3Ease of manufacture
If the same material is used for both the via and the conductive filling, then manufacturing simplicity is maintained, but material migration occurs compromising structural integrity
Solution Approach 1:
The refractory metal liner serves as an intermediary barrier between the via material and the conductive filling material. This liner prevents direct contact and potential migration between the two materials, thereby maintaining structural stability and compositional integrity while allowing different materials to be used for the via and filling.
4Productivity
If cavities are left within the via, then the fabrication process is simpler, but defects increase affecting IC operation
Solution Approach 1:
The refractory metal liner is deposited as an intermediary layer on the via interior surface before filling with conductive material. This liner creates a controlled interface that prevents material migration and eliminates cavity formation, thereby reducing defects and improving IC reliability while maintaining a systematic fabrication approach.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively reduces defects and electrical resistance, enhances the stability of the IC by preventing material migration and ensuring reliable current flow, and allows for the use of different material compositions to improve the structural integrity and performance of the IC.
Implementation Method 1
forming a metal plug within the cavity to the surface of the via, such that the metal plug conformally contacts a sidewall of the cavity and the interior surface of the via
Implementation Method 2
a refractory metal liner positioned on the metal plug of the via, wherein the refractory metal liner separates the metal plug from a contact positioned over the via
Data Source
AI summary
Aspects of the present disclosure include integrated circuit (IC) structures with metal plugs therein, and methods of forming the same. An IC fabrication method according to embodiments of the present disclosure can include: providing a structure including a via including a bulk semiconductor material therein, wherein the via further includes a cavity extending from a top surface of the via to an interior surface of the via, and wherein a portion of the bulk semiconductor material defines at least one sidewall of the cavity; forming a first metal level on the via, wherein the first metal level includes a contact opening positioned over the cavity of the via; forming a metal plug within the cavity to the surface of the via, such that the metal plug conformally contacts a sidewall of the cavity and the interior surface of the via, wherein the metal plug is laterally distal to an exterior sidewall of the via; and forming a contact within the contact opening of the first metal level.